Question about 2000 GMC New Sierra 1500

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2002 5.3 L long cranking to start after warmed up. replaced fuel pump w/ same problem Code reader showed PO307 fuel misfire but only showed once then O-Codes. Injectors all sound funtioning. Could bad O-ring cause fuel pressure loss ?

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  • bigcatfelix Jan 02, 2011

    where exactly is fpr located ? and my OBD-2 read po307 fuel misfire !

  • bigcatfelix Jan 02, 2011

    PS my vehicle is a 2002 5.3 L w/ 72k mi Thanks

  • bigcatfelix Jan 02, 2011

    Thanks I'll try your ideas and let you know, It might take a couple of days to get to it. The weather is bad at this time, and us wimpy Californians can't handle the cold weather and rain !!

  • bigcatfelix Jan 03, 2011

    Yes thank you, I pulled the small hose @ FPR and fuel dribbeled out ! replaced the FPR and it seems to have solved my PROBLEM !! Thanks again



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Yes bad o-ring seal in the fuel pressure regulator could be the problem causing the loss of fuel pressure. Also bad o-rings on injectors can also cause loss of fuel pressure.Also check the FPR itself.If fuel pressure regular is faulty,then also there will be loss of fuel pressure. Also check for leak at injectors:-- What you do to check for an injector leak is pressurize your fuel system (key on) with a fuel pressure guage attached to the service port. Then close both valves on the return and feed block off lines and monitor your guage. If the system keeps pressure you know that injectors are ok and the problem may be down stream (fuel pump or fpr). On the flip side, if it didn't hold pressure then it could be an injector or an fpr leaking into the vacuum line. To check the fuel pump, presurize the fuel system and only block off only the return line. If it holds pressure then you know the the fuel pump is ok and the problem may be with the fpr. If you loose pressure, the pump check valve is bad and you need a fuel pump. To check the fpr, pressurize the system and then block off only the feed line. If the system holds pressure then the fpr is ok. If you loose pressure then the fpr is allowing fuel to pass into the return line. In that case you have a bad fpr. ------------ Try this tests and possibilities to confirm the fault.This should help.Thanks.Helpmech.

Posted on Jan 02, 2011

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  • raj somaiya Jan 02, 2011

    Fuel pressure regulator is located on the DRIVERS side fuel rail about half way, and has a small hard vacuum line going to it one end and the intake other end.Check the fuel pressure regulator for ANY sign of fuel. If you remove the vacuum line from regulator and there is ANY gas, it is faulty.
    These injectors have a funnel shaped screen at the top.Check if the injectors are clogged there.If yes then clean the injectors and see.
    You can use wd-40 spray to clean.------------ This should help.Thanks.Helpmech.

  • raj somaiya Jan 02, 2011

    Keep updated with the tests/results.Thanks .Helpmech.

  • raj somaiya Jan 03, 2011

    Thanks.for the update.



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